1. Field of the Invention
The present invention relates to a process for the preparation of 2-perfluoropropoxy-perfluoropropionyl fluoride by dimerization of perfluoropropene epoxide (PFPO).
2. Description of the Prior Art
PFPO polymerization is known and disclosed in U.S. Pat. No. 3,322,826.
U.K. Pat. No. 1,550,268 discloses the preparation of PFPO oligomers in aprotic polar solvent at temperatures of from -50.degree. C. to +20.degree. C. in the presence of N,N,N',N'-tetrasubstituted diaminodifluoromethane as catalyst; oligomers are obtained which can be represented by the following general formula: ##STR1## wherein R.sub.F represents a perfluoroalkyl chain containing from 1 to 8 carbon atoms, and n ranges from 0 to 4.
According to this patent, it is recommended to operate by carefully controlling the reaction temperature because, in order to obtain high yields in dimer, due to the low boiling point of PFPO (-29.degree. C.), maintaining the temperature within the range of from 0.degree. C. to 20.degree. C. with high PFPO concentrations and under increased pressure is necessary. The reaction times result however to be rather long, of the order of 24 hours. The trimers, tetramers and pentamers are obtained on the contrary by operating at temperatures comprised within the range of from -15.degree. C. to -30.degree. C., under atmospheric pressure and with low PFPO concentrations.